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A WEEKLY ILLUSTRATED JOURNAL OF SCIENCE. 



" To the solid ground 

 Of Nature trusts the mind which builds for aye." — Wordsworth. 



No. 1673, Vol. 65] 



THURSDAY, NOVEMBER 21, 1901. 



[Price Sixpence. 



Registered as a Newspaper at the General Post Office.] 



ELECTRIC LANTERN. 



NEW PATTERN CHEAP ELECTRIC LANTERN, 

 fitted with Hand-feed Arc Lamp in Case, £10 10s. 



Afeiv Season's List of Lanterns and Slides post free. 



3v E 'w T o wr ^ 00., 



OPTICIANS, &e., TO THE KING, 

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X-RAY TUBES. 



Special arrangement 

 for the 



REGULATION OF THE 

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 ;^ heavy discharge 



TUBES 



for Uie uitli /^ '^"\ 



ELECTROLYTIC (f 

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Send for our 

 Haw Price List. 



JOHN J. GRIFFIN & SONS, Ltd., 



20-26 SARDINIA STREET, LINCOLN'S INN FIELDS, 

 LONDON, W.C. 



FOR ALL 

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LENS ^i^HHElL Ojf^ 



4 ♦^ In 3 Series. ^r^% 



<^» I. GENKR.\L. ^^ 



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-^# III. SEECIAL PROCESS. ^>i 



This rapid, wide, medium or narrow angle lens all in one is 



_ suitable for all work. 



/•"ull Catalogue free on application to the Manufacturers : — • 



R. <& J. BSCK:, ILitcl., 



68 CORNHILL, LONDON, E.C. 



SPECTACLES 

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And other Powerful Illuminants. 



NEGRETTI & ZAMBRA'S 

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Protect the Eyes from Gl.ire, and 



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N. and Z.'s SPORTING SPECTACLES, close-fitting and having extra 

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frustrated Price Lists of Optical and Meteorological Instruments, 

 Free by Post to all parts of the World. 



N E G R ETTI and ZA M B R A, 

 38 HOLBORN VIADUCT, E.G. 



